JP2019186085A - Sulfide-based inorganic solid electrolyte material, solid electrolyte, solid electrolyte membrane, and lithium ion battery - Google Patents

Abstract

To provide a sulfide-based inorganic solid electrolyte material having excellent balance between electrochemical stability and lithium ion conductivity.SOLUTION: The sulfide-based inorganic solid electrolyte material has lithium ion conductivity. In spectra obtained by X-ray diffraction using CuKα rays as a radiation source, peaks are present at positions of diffraction angle 2θ=17.2±0.5° and a diffraction angle 2θ=29.2±0.8°. When maximum diffraction intensity of the diffraction peak present at the diffraction angle 2θ=17.2±0.5° is denoted as Iand maximum diffraction intensity of the diffraction peak present at the diffraction angle 2θ=29.2±0.8° is denoted as I, a value of I/Iis 0.92 or more.SELECTED DRAWING: None

Description

  The present invention relates to a sulfide-based inorganic solid electrolyte material, a solid electrolyte, a solid electrolyte membrane, and a lithium ion battery.

  Lithium ion batteries are generally used as a power source for small portable devices such as mobile phones and notebook computers. Recently, in addition to small portable devices, lithium ion batteries have begun to be used as power sources for electric vehicles and power storage.

  An electrolyte solution containing a flammable organic solvent is used in a lithium ion battery currently on the market. On the other hand, a lithium ion battery (hereinafter also referred to as an all-solid-state lithium ion battery) in which the electrolyte is changed to a solid electrolyte to make the battery completely solid does not use a flammable organic solvent in the battery. It is considered that the manufacturing cost and productivity are excellent.

  As a solid electrolyte material used for such a solid electrolyte, for example, a sulfide-based inorganic solid electrolyte material is known.

Patent Document 1 (Japanese Patent Laid-Open No. 2016-27545) has a peak at a position of 2θ = 29.86 ° ± 1.00 ° in X-ray diffraction measurement using CuKα rays, and Li _{2y + 3} PS ₄ (0 .1 ≦ y ≦ 0.175), a sulfide-based solid electrolyte material is described.

JP 2016-27545 A

However, although sulfide-based inorganic solid electrolyte materials are excellent in electrochemical stability and lithium ion conductivity, they are still low in lithium ion conductivity compared to electrolytes and are not sufficiently satisfactory as solid electrolyte materials. There wasn't.
From the above, sulfide-based inorganic solid electrolyte materials used for lithium ion batteries are required to further improve lithium ion conductivity while having electrochemical stability.

  The present invention has been made in view of the above circumstances, and provides a sulfide-based inorganic solid electrolyte material having an excellent balance between electrochemical stability and lithium ion conductivity.

  In order to provide a sulfide-based inorganic solid electrolyte material having an excellent balance between electrochemical stability and lithium ion conductivity, the present inventors have intensively studied the X-ray diffraction profile of the sulfide-based inorganic solid electrolyte material. As a result, in a spectrum obtained by X-ray diffraction using CuKα rays as a radiation source, a diffraction angle 2θ = 17.2 ± 0.00 with respect to a diffraction peak existing at a diffraction angle 2θ = 29.2 ± 0.8 °. The inventors have found that a sulfide-based inorganic solid electrolyte material having a diffraction peak ratio at a position of 5 ° having a specific value or more has an excellent balance between electrochemical stability and lithium ion conductivity.

That is, according to the present invention,
A sulfide-based inorganic solid electrolyte material having lithium ion conductivity,
In the spectrum obtained by X-ray diffraction using CuKα ray as the radiation source, there are peaks at the diffraction angle 2θ = 17.2 ± 0.5 ° and the diffraction angle 2θ = 29.2 ± 0.8 °, respectively. And
Maximum diffraction of the diffraction peak maximum diffraction intensity of a diffraction peak at the position of the diffraction angle 2θ = 17.2 ± 0.5 ° and _{I A,} at the position of the diffraction angle 2θ = 29.2 ± 0.8 ° when the strength was _{I B,
A} sulfide-based inorganic solid electrolyte material having a value of I _A / I _B of 0.92 or more is provided.

Moreover, according to the present invention,
A sulfide-based inorganic solid electrolyte material having lithium ion conductivity,
After heat treatment at 270 ° C. for 2 hours, in a spectrum obtained by X-ray diffraction using CuKα rays as a radiation source, a diffraction angle 2θ = 17.2 ± 0.5 ° and a diffraction angle 2θ = 29.2 ± 0. Each has a peak at 8 °,
Maximum diffraction of the diffraction peak maximum diffraction intensity of a diffraction peak at the position of the diffraction angle 2θ = 17.2 ± 0.5 ° and _{I A,} at the position of the diffraction angle 2θ = 29.2 ± 0.8 ° when the strength was _{I B,
A} sulfide-based inorganic solid electrolyte material having a value of I _A / I _B of 0.92 or more is provided.

Furthermore, according to the present invention,
A solid electrolyte containing the sulfide-based inorganic solid electrolyte material is provided.

Furthermore, according to the present invention,
There is provided a solid electrolyte membrane containing the solid electrolyte as a main component.

Furthermore, according to the present invention,
A lithium ion battery comprising a positive electrode including a positive electrode active material layer, an electrolyte layer, and a negative electrode including a negative electrode active material layer,
There is provided a lithium ion battery in which at least one of the positive electrode active material layer, the electrolyte layer, and the negative electrode active material layer contains the sulfide-based inorganic solid electrolyte material.

  ADVANTAGE OF THE INVENTION According to this invention, the sulfide type inorganic solid electrolyte material which is excellent in the balance of electrochemical stability and lithium ion conductivity can be provided.

It is sectional drawing which shows an example of the structure of the lithium ion battery of embodiment which concerns on this invention. It is a figure which shows the X-ray-diffraction spectrum of the sulfide type inorganic solid electrolyte material obtained in Example 1 and Comparative Example 1. FIG. 6 is a diagram showing X-ray diffraction spectra of sulfide-based inorganic solid electrolyte materials obtained in Example 2 and Comparative Example 2. FIG. FIG. 4 is a diagram showing X-ray diffraction spectra of sulfide-based inorganic solid electrolyte materials obtained in Example 3 and Comparative Example 3.

  Embodiments of the present invention will be described below with reference to the drawings. In all the drawings, similar constituent elements are denoted by common reference numerals, and description thereof is omitted as appropriate. Moreover, the figure is a schematic diagram and does not match the actual dimensional ratio. “A to B” in the numerical range represents A or more and B or less unless otherwise specified.

[Sulfide-based inorganic solid electrolyte materials]
First, the sulfide-based inorganic solid electrolyte material according to the present embodiment will be described.
The sulfide-based inorganic solid electrolyte material according to the present embodiment is a sulfide-based inorganic solid electrolyte material having lithium ion conductivity, and has a diffraction angle 2θ in a spectrum obtained by X-ray diffraction using CuKα rays as a radiation source. = 17.2 ± 0.5 ° and diffraction angle 2θ = 29.2 ± 0.8 °, respectively, with a peak at diffraction angle 2θ = 17.2 ± 0.5 ° when the maximum diffraction intensity of a diffraction peak and _{I a,} the maximum diffraction intensity of a diffraction peak at the position of the diffraction angle 2θ = 29.2 ± 0.8 ° was _{I B,} the value of I a / _{I B} is 0 .92 or more, preferably 0.95 or more, more preferably 1.0 or more, and particularly preferably 1.1 or more.
The upper limit of the value of I _A / _{I B} is not particularly limited, for example 5.0 or less, preferably 3.0 or less, more preferably 2.0 or less, more preferably 1.5 or less.
Also, the sulfide-based inorganic solid electrolyte material according to the present embodiment, after heat treatment for 2 hours at 270 ° C., the value of I A _/ I _B may be configured to be less than the above lower limit. In this case, as the value of I A _/ I _B is less than the above lower limit, it is preferable to use a sulfide-based inorganic solid electrolyte material after heating the sulfide-based inorganic solid electrolyte material.

Sulfide-based inorganic solid electrolyte material according to this embodiment, by the value of I A _/ I _B and less than the above lower limit, while maintaining a good electrochemical stability, to improve lithium ion conductivity Can do.
Although the reason for this is not necessarily clear, the following reason is presumed.
First, _Li 3 representative conventional sulfide-based inorganic solid electrolyte material of PS _{4, etc.,} XRD data of I A / _{I B} values are known to be 0.91 or less _(Li 3 PS ₄ JCPDS (Joint Committee on Powder Diffraction Standards) card No. 01-076-0973).
However, sulfide-based inorganic solid electrolyte material according to the present embodiment, the value of I _{A /} I _B is higher than the conventional typical sulfide-based inorganic solid electrolyte material, such as Li ₃ PS _4. Therefore, it is considered that the sulfide-based inorganic solid electrolyte material according to the present embodiment has a novel structure different from the conventional sulfide-based inorganic solid electrolyte material. Such a novel structure is considered to be a structure in which lithium ions hop more easily. Therefore, the sulfide-based inorganic solid electrolyte material according to the present embodiment is excellent in lithium ion diffusibility, and as a result, exhibits higher ionic conductivity than conventional representative sulfide-based inorganic solid electrolyte materials. it is conceivable that.
Therefore, it is considered that the value of I _A / I _B is not less than the above lower limit value indicates that a new structure different from the conventional typical sulfide-based inorganic solid electrolyte material is formed. .
Step value of the I _{A /} I _B of the sulfide-based inorganic solid electrolyte material according to the present embodiment, vitrifying the inorganic composition is that or raw materials for adjusting the composition ratio of the sulfide-based inorganic solid electrolyte material In this case, it is possible to prevent the contact of moisture or oxygen with the inorganic composition at a higher level than before, or heat treatment at a high temperature of 220 ° C. or higher.

The sulfide-based inorganic solid electrolyte material according to the present embodiment backs the maximum diffraction intensity at a diffraction angle 2θ = 35.0 ± 0.1 ° in a spectrum obtained by X-ray diffraction using CuKα rays as a radiation source. When the ground strength is I ₀ , the value of I _A / I ₀ is preferably 8.0 or more, more preferably 8.5 or more.
By setting the value of I _A / I ₀ to be the above lower limit value or more, lithium ion conductivity can be further improved.
In the sulfide-based inorganic solid electrolyte material according to the present embodiment, the upper limit value of I _A / I ₀ is not particularly limited, but is, for example, 30.0 or less, preferably 20.0 or less, and more preferably 15. 0 or less.
In addition, the sulfide-based inorganic solid electrolyte material according to the present embodiment may be configured such that the value of I _A / I ₀ falls within the above range after heat treatment at 270 ° C. for 2 hours.
The value of I _A / I ₀ of the sulfide-based inorganic solid electrolyte material according to the present embodiment is a step of adjusting the composition ratio of the sulfide-based inorganic solid electrolyte material or vitrifying the raw inorganic composition In this case, it is possible to prevent the contact of moisture or oxygen with the inorganic composition at a higher level than before, or heat treatment at a high temperature of 220 ° C. or higher.

The sulfide-based inorganic solid electrolyte material according to the present embodiment backs the maximum diffraction intensity at a diffraction angle 2θ = 35.0 ± 0.1 ° in a spectrum obtained by X-ray diffraction using CuKα rays as a radiation source. When the ground strength is I ₀ , the value of I _B / I ₀ is preferably 5.0 or more, more preferably 6.0 or more.
By setting the value of I _B / I ₀ to the above lower limit value or more, lithium ion conductivity can be further improved.
In the sulfide-based inorganic solid electrolyte material according to this embodiment, the upper limit value of I _B / I ₀ is not particularly limited, but is, for example, 30.0 or less, preferably 20.0 or less, and more preferably 15. 0 or less.
In addition, the sulfide-based inorganic solid electrolyte material according to the present embodiment may be configured such that the value of I _B / I ₀ falls within the above range after heat treatment at 270 ° C. for 2 hours.
The value of I _B / I ₀ of the sulfide-based inorganic solid electrolyte material according to the present embodiment can be realized by adjusting the composition ratio of the sulfide-based inorganic solid electrolyte material.

In addition, in the sulfide-based inorganic solid electrolyte material according to the present embodiment, a diffraction peak appears at a diffraction angle 2θ = 25.6 ± 0.5 ° in a spectrum obtained by X-ray diffraction using CuKα rays as a radiation source. Furthermore, you may have. By having this diffraction peak, lithium ion conductivity can be further improved.
In addition, the sulfide-based inorganic solid electrolyte material according to the present embodiment has a diffraction angle 2θ = 25.6 ± in a spectrum obtained by X-ray diffraction using CuKα rays as a radiation source after heat treatment at 270 ° C. for 2 hours. The structure which further has a diffraction peak in the position of 0.5 degree may be sufficient.

The sulfide-based inorganic solid electrolyte material according to the present embodiment contains Li, P, and S as constituent elements from the viewpoint of further improving electrochemical stability, stability in moisture and air, and handleability. It is preferable.
In addition, the sulfide-based inorganic solid electrolyte material according to the present embodiment is the sulfide from the viewpoint of further improving lithium ion conductivity, electrochemical stability, stability in moisture and air, and handleability. The molar ratio Li / P of the content of Li to the content of P in the inorganic inorganic solid electrolyte material is preferably 1.0 or more and 5.0 or less, more preferably 2.0 or more and 4.5 or less. Yes, more preferably from 3.0 to 4.2, even more preferably from 3.2 to 4.0, particularly preferably from 3.3 to 3.8, and the inclusion of P The molar ratio S / P of the content of S to the amount is preferably 2.0 or more and 6.0 or less, more preferably 3.0 or more and 5.0 or less, and further preferably 3.5 or more and 4 or less. .5 or less, particularly preferably 3 8 more than 4.2 is less than or equal to.
Here, the contents of Li, P, and S in the sulfide-based inorganic solid electrolyte material according to the present embodiment can be determined by, for example, ICP emission spectroscopic analysis or X-ray analysis.

In the sulfide-based inorganic solid electrolyte material according to the present embodiment, lithium ion conduction of the sulfide-based inorganic solid electrolyte material by the AC impedance method under measurement conditions of 27.0 ° C., an applied voltage of 10 mV, and a measurement frequency range of 0.1 Hz to 7 MHz. The degree is preferably 1.1 × 10 ⁻³ S · cm ⁻¹ or more.
When the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material according to the present embodiment is not less than the above lower limit value, a lithium ion battery that is more excellent in battery characteristics can be obtained. Further, when such a sulfide-based inorganic solid electrolyte material is used, a lithium ion battery having further excellent input / output characteristics can be obtained.

Examples of the shape of the sulfide-based inorganic solid electrolyte material according to the present embodiment include a particulate shape.
The particulate sulfide-based inorganic solid electrolyte material according to the present embodiment is not particularly limited, but the average particle size d ₅₀ in the weight-based particle size distribution by the laser diffraction scattering type particle size distribution measurement method is preferably 1 μm or more and 100 μm or less. More preferably, they are 3 micrometers or more and 80 micrometers or less, More preferably, they are 5 micrometers or more and 60 micrometers or less.
The average particle size d ₅₀ of the sulfide-based inorganic solid electrolyte material to be in the above range, it is possible to further improve the lithium ion conductivity while maintaining good handling properties.

The sulfide-based inorganic solid electrolyte material according to the present embodiment is excellent in electrochemical stability. Here, the electrochemical stability means, for example, a property that is not easily oxidized and reduced in a wide voltage range. More specifically, in the sulfide-based inorganic solid electrolyte material according to the present embodiment, the sulfide-based inorganic solid electrolyte material measured under the conditions of a temperature of 25 ° C., a sweep voltage range of 0 to 5 V, and a voltage sweep rate of 5 mV / sec. Is preferably 0.50 μA or less, more preferably 0.20 μA or less, even more preferably 0.10 μA or less, and even more preferably 0.05 μA or less. It is particularly preferably 0.03 μA or less.
It is preferable that the maximum value of the oxidative decomposition current of the sulfide-based inorganic solid electrolyte material is not more than the above upper limit value because oxidative decomposition of the sulfide-based inorganic solid electrolyte material in the lithium ion battery can be suppressed.
The lower limit of the maximum value of the oxidative decomposition current of the sulfide-based inorganic solid electrolyte material is not particularly limited, but is, for example, 0.0001 μA or more.

The sulfide-based inorganic solid electrolyte material according to this embodiment can be used for any application that requires lithium ion conductivity. Especially, it is preferable that the sulfide type inorganic solid electrolyte material which concerns on this embodiment is used for a lithium ion battery. More specifically, it is used for a positive electrode active material layer, a negative electrode active material layer, an electrolyte layer and the like in a lithium ion battery. Furthermore, the sulfide-based inorganic solid electrolyte material according to the present embodiment is suitably used for a positive electrode active material layer, a negative electrode active material layer, a solid electrolyte layer, etc. that constitute an all solid-state lithium ion battery. It is particularly preferably used for a solid electrolyte layer constituting a battery.
As an example of the all-solid-state lithium ion battery to which the sulfide-based inorganic solid electrolyte material according to the present embodiment is applied, one in which a positive electrode, a solid electrolyte layer, and a negative electrode are stacked in this order can be given.

[Method for producing sulfide-based inorganic solid electrolyte material]
Next, the manufacturing method of the sulfide type inorganic solid electrolyte material which concerns on this embodiment is demonstrated.
The method for producing a sulfide-based inorganic solid electrolyte material according to this embodiment is different from the conventional method for producing a sulfide-based inorganic solid electrolyte material. That is, the sulfide-based inorganic solid electrolyte material values of I A _/ I _B is not less than the lower limit, or be highly controlled (1) composition ratio of the sulfide-based inorganic solid electrolyte material, (2) raw material In the process of vitrifying the inorganic composition, the contact between moisture and oxygen and the inorganic composition is prevented at a higher level than before, (3) heat treatment at a high temperature of 220 ° C. or higher, etc. It can be obtained only by adopting the contrivance points.
Here, when the step (3) is performed, the film formability of the sulfide-based inorganic solid electrolyte material may be lowered. Therefore, the step (3) is performed after the solid electrolyte membrane is formed. Also good. That is, the sulfide-based inorganic solid electrolyte material according to the present embodiment includes a sulfide-based inorganic solid electrolyte material in a state before the step (3) is performed.
However, the sulfide-based inorganic solid electrolyte material according to this embodiment is based on the premise that the above-mentioned three manufacturing methods are adopted, and there are various specific manufacturing conditions such as mixing conditions of various raw materials. Can be adopted.
Hereinafter, the method for producing a sulfide-based inorganic solid electrolyte material according to the present embodiment will be described more specifically.

The sulfide-based inorganic solid electrolyte material according to this embodiment can be obtained, for example, by a production method including the following steps (A), (B), and (C). Moreover, the manufacturing method of the sulfide type inorganic solid electrolyte material which concerns on this embodiment may further include the following processes (D) as needed.
Step (A): Step of preparing a raw material inorganic composition containing two or more inorganic compounds as raw materials Step (B): In an atmosphere in which the abundance and inflow of moisture and oxygen are suppressed at a higher level than before, A process of obtaining a glassy sulfide-based inorganic solid electrolyte material by mechanically treating the raw material inorganic composition to vitrify the inorganic compounds as raw materials while chemically reacting them. Step (C) Step of heating the sulfide-based inorganic solid electrolyte material and crystallizing at least part thereof Step (D): Step of pulverizing, classifying, or granulating the obtained sulfide-based inorganic solid electrolyte material

  According to the method for producing a sulfide-based inorganic solid electrolyte material according to the present embodiment, the amount of moisture and oxygen in the atmosphere and the amount of moisture and oxygen in the atmosphere in the vitrification step are compared with the conventional production method. Inflow is suppressed at a higher level than before. Therefore, according to the method for manufacturing a sulfide-based inorganic solid electrolyte material according to the present embodiment, oxygen and moisture taken in at the time of manufacturing the sulfide-based inorganic solid electrolyte material can be suppressed at a high level. It is considered that a sulfide-based inorganic solid electrolyte material having a novel structure different from that can be realized.

(Step of preparing raw material inorganic composition (A))
First, a raw material inorganic composition containing two or more kinds of inorganic compounds such as lithium sulfide, phosphorus sulfide, and lithium nitride as raw materials in a specific ratio is prepared. Here, the mixing ratio of each raw material in the raw material inorganic composition is adjusted so that the obtained sulfide-based inorganic solid electrolyte material has a desired composition ratio.
The method of mixing each raw material is not particularly limited as long as each raw material can be mixed uniformly. For example, a ball mill, a bead mill, a vibration mill, a blow mill, a mixer (pug mixer, ribbon mixer, tumbler mixer, drum) Mixer, V-type mixer, etc.), kneader, biaxial kneader, airflow pulverizer and the like.
Mixing conditions such as agitation speed, processing time, temperature, reaction pressure, and gravitational acceleration applied to the mixture can be appropriately determined depending on the amount of the mixture processed.

It does not specifically limit as lithium sulfide used as a raw material, Commercially available lithium sulfide may be used, for example, lithium sulfide obtained by reaction of lithium hydroxide and hydrogen sulfide may be used. From the viewpoint of obtaining a high-purity sulfide-based inorganic solid electrolyte material and suppressing side reactions, it is preferable to use lithium sulfide with less impurities.
Here, in this embodiment, lithium polysulfide is also included in lithium sulfide.

Is not particularly limited as phosphosulfurized used as a raw material, it is possible to use phosphorus sulfide which is commercially available _{(e.g., P 2 S 5, P 4} S 3, P 4 S 7, P 4 S 5 , etc.). From the viewpoint of obtaining a high-purity sulfide-based inorganic solid electrolyte material and suppressing side reactions, it is preferable to use phosphorus sulfide with less impurities. Further, instead of phosphorus sulfide, simple phosphorus (P) and simple sulfur (S) in a corresponding molar ratio can be used. Simple phosphorus (P) and simple sulfur (S) can be used without particular limitation as long as they are industrially produced and sold.

Lithium nitride may be used as a raw material. Here, since nitrogen in lithium nitride is discharged into the system as N ₂ , a sulfide-based inorganic solid containing Li, P, and S as constituent elements by using lithium nitride as an inorganic compound as a raw material Only the Li composition can be increased with respect to the electrolyte material.
Is not particularly restricted but includes lithium nitride according to the present embodiment, the lithium nitride are commercially available (for example, Li 3 _N, etc.) may be used, for example, metallic lithium (eg, Li foil) and a nitrogen gas Lithium nitride obtained by the above reaction may be used. From the viewpoint of obtaining a high-purity solid electrolyte material and suppressing side reactions, it is preferable to use lithium nitride with less impurities.

(Step of obtaining a glassy sulfide-based inorganic solid electrolyte material (B))
Next, by virtue of mechanical treatment of the raw inorganic composition in an atmosphere in which the abundance and inflow of moisture and oxygen are suppressed at a higher level than before, the raw material inorganic compound is vitrified while chemically reacting with each other. A glassy sulfide-based inorganic solid electrolyte material is obtained.

Here, the mechanical treatment can be vitrified while causing a chemical reaction by mechanically colliding two or more inorganic compounds, and examples thereof include mechanochemical treatment. Here, the mechanochemical treatment is a method of vitrification while applying mechanical energy such as shearing force or collision force to the target composition.
In the step (B), the mechanochemical treatment is preferably a dry mechanochemical treatment from the viewpoint of easily realizing an environment in which moisture and oxygen are removed at a high level.
When mechanochemical treatment is used, each raw material can be mixed while being pulverized into fine particles, so that the contact area of each raw material can be increased. Thereby, since reaction of each raw material can be accelerated | stimulated, the sulfide type inorganic solid electrolyte material which concerns on this embodiment can be obtained still more efficiently.

  Here, the mechanochemical treatment is a method of vitrification while applying mechanical energy such as shearing force, collision force or centrifugal force to the object to be mixed. Equipment for vitrification by mechanochemical treatment (hereinafter referred to as vitrification equipment) includes ball mills, bead mills, vibration mills, turbo mills, mechano-fusions, disc mills, roll mills, etc .; rock drills and vibrations Examples thereof include a rotation / striking pulverizer composed of a combination of rotation (shear stress) and impact (compression stress) represented by a drill, an impact driver, etc .; a high-pressure type grinding roll; Among these, a ball mill and a bead mill are preferable, and a ball mill is particularly preferable from the viewpoint that very high impact energy can be efficiently generated. In addition, from the viewpoint of excellent continuous productivity, a roll mill; a rotary and impact crushing device consisting of a combination of rotation (shear stress) and impact (compression stress) represented by rock drills, vibratory drills, impact drivers, etc. A high-pressure type grinding roll;

In order to obtain the sulfide-based inorganic solid electrolyte material according to the present embodiment, it is important that the step (B) is performed in an atmosphere in which the abundance and inflow of moisture and oxygen are suppressed at a higher level than before. It is. Thereby, contact with a raw material inorganic composition, a water | moisture content, and oxygen can be suppressed at a higher level than before.
Here, the atmosphere in which the abundance and inflow of moisture and oxygen are suppressed at a higher level than before can be created, for example, by the following method.
First, the mixing container and the closed container for the vitrification apparatus are arranged in the glove box, and then the inertness such as high-purity dry argon gas or dry nitrogen gas obtained through the gas refining apparatus in the glove box. Gas injection and vacuum deaeration are performed a plurality of times (preferably 3 times or more). Here, in the glove box after the above operation, an inert gas such as high-purity dry argon gas or dry nitrogen gas is circulated through a gas purification device, so that the oxygen concentration and the water concentration are preferably 1.0 ppm or less. Preferably, it is adjusted to 0.8 ppm or less, more preferably 0.6 ppm or less.
Next, two or more inorganic compounds are put into a mixing container in the glove box, and then mixed to prepare a raw material inorganic composition (meaning step (A)). Here, the introduction of two or more kinds of inorganic compounds into the mixing container in the glove box is performed according to the following procedure. First, with the door inside the glove box body closed, two or more inorganic compounds are put into the side box of the glove box. Next, injection of inert gas such as high-purity dry argon gas and dry nitrogen gas drawn from the inside of the glove box and vacuum deaeration are performed a plurality of times (preferably 3 times or more), and thereafter Then, the door inside the main body of the glove box is opened, two or more kinds of inorganic compounds are put into the mixing container inside the main body of the glove box, and the mixing container is sealed.
Subsequently, after mixing 2 or more types of inorganic compounds, the obtained raw inorganic composition is taken out from the mixing container, transferred to a container for a vitrification apparatus, and sealed.
By performing such an operation, the amount of moisture and oxygen in the sealed container containing the raw material inorganic composition can be suppressed at a higher level than before, and as a result, in step (B), An atmosphere in which the abundance is suppressed at a higher level than before can be created.
Subsequently, the sealed container containing the raw material inorganic composition is taken out from the glove box. Next, a vitrification apparatus arranged in an atmosphere filled with dry gas such as dry argon gas, dry nitrogen gas, and dry air (for example, in a box filled with dry argon gas, dry nitrogen gas, dry air, etc.) Set an airtight container to vitrify. Here, during vitrification, it is preferable to continue introducing a certain amount of dry gas into the atmosphere filled with dry gas. By performing such a device, in step (B), it is possible to create an atmosphere in which the inflow of moisture and oxygen is suppressed at a higher level than before.
In addition, from the viewpoint of suppressing the inflow of moisture and oxygen into the sealed container at a high level, the lid of the sealed container has a packing excellent in sealing performance such as an O-ring and a ferrule packing from the viewpoint of realizing higher airtightness. Is preferably used.

The mixing conditions such as the rotational speed, processing time, temperature, reaction pressure, and gravitational acceleration applied to the raw inorganic composition when mechanically processing the raw inorganic composition are appropriately determined depending on the type and the processing amount of the raw inorganic composition. be able to. In general, the faster the rotation speed, the faster the glass production rate, and the longer the treatment time, the higher the conversion to glass.
Usually, when X-ray diffraction analysis using CuKα ray as a radiation source is performed, if the diffraction peak derived from the raw material disappears or decreases, the raw material inorganic composition is vitrified, and the desired sulfide-based inorganic solid electrolyte material Can be determined.

Here, in the step (B), the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material by the alternating current impedance method under the measurement conditions of 27.0 ° C., the applied voltage of 10 mV, and the measurement frequency range of 0.1 Hz to 7 MHz is preferably 1.0 × 10 ⁻⁴ S · cm ⁻¹ or more, more preferably 2.0 × 10 ⁻⁴ S · cm ⁻¹ or more, further preferably 3.0 × 10 ⁻⁴ S · cm ⁻¹ or more, particularly preferably Is preferably vitrified until it becomes 4.0 × 10 ⁻⁴ S · cm ⁻¹ or more. As a result, a sulfide-based inorganic solid electrolyte material that is more excellent in lithium ion conductivity can be obtained.

(Step of crystallizing at least a part of the sulfide-based inorganic solid electrolyte material (C))
Subsequently, by heating the obtained sulfide-based inorganic solid electrolyte material in a glass state, at least a part of the sulfide-based inorganic solid electrolyte material is crystallized to be in a glass ceramic state (also referred to as crystallized glass). A sulfide-based inorganic solid electrolyte material is produced. By doing so, a sulfide-based inorganic solid electrolyte material having further excellent lithium ion conductivity can be obtained.
That is, the sulfide-based inorganic solid electrolyte material according to this embodiment is preferably in a glass ceramic state (crystallized glass state) from the viewpoint of excellent lithium ion conductivity.

The temperature when heating the glassy sulfide-based inorganic solid electrolyte material is preferably in the range of 220 ° C. or higher and 500 ° C. or lower, and more preferably in the range of 250 ° C. or higher and 350 ° C. or lower.
The time for heating the glassy sulfide-based inorganic solid electrolyte material is not particularly limited as long as it is a time for obtaining a desired glass-ceramic-state sulfide-based inorganic solid electrolyte material. It is within the range of not less than 24 hours and not more than 1 hour, preferably not less than 1 hour and not more than 3 hours. The heating method is not particularly limited, and examples thereof include a method using a firing furnace. In addition, conditions, such as temperature and time at the time of such a heating, can be suitably adjusted in order to optimize the characteristic of the sulfide type inorganic solid electrolyte material which concerns on this embodiment.

Moreover, it is preferable to heat the sulfide-type inorganic solid electrolyte material in a glass state in, for example, an inert gas atmosphere. Thereby, deterioration (for example, oxidation) of sulfide system inorganic solid electrolyte material can be prevented.
Examples of the inert gas when heating the sulfide inorganic solid electrolyte material in the glass state include argon gas, helium gas, nitrogen gas, and the like. These inert gases are preferably higher in purity in order to prevent impurities from entering the product, and in order to avoid contact with moisture, the dew point is preferably −70 ° C. or lower, and −80 It is particularly preferable that the temperature is not higher than ° C. The method of introducing the inert gas into the mixed system is not particularly limited as long as the mixed system is filled with an inert gas atmosphere. However, the inert gas is purged, and a constant amount of inert gas is continuously introduced. Methods and the like.

(Step of grinding, classifying or granulating (D))
In the method for producing a sulfide-based inorganic solid electrolyte material according to this embodiment, a step of pulverizing, classifying, or granulating the obtained sulfide-based inorganic solid electrolyte material may be further performed as necessary. For example, a sulfide-based inorganic solid electrolyte material having a desired particle diameter can be obtained by making fine particles by pulverization and then adjusting the particle diameter by classification operation or granulation operation. It does not specifically limit as said grinding | pulverization method, Well-known grinding | pulverization methods, such as a mixer, airflow grinding | pulverization, a mortar, a rotary mill, a coffee mill, can be used. Moreover, it does not specifically limit as said classification method, Well-known methods, such as a sieve, can be used.
These pulverization or classification are preferably performed in an inert gas atmosphere or a vacuum atmosphere from the viewpoint that contact with moisture in the air can be prevented.

  In order to obtain the sulfide-based inorganic solid electrolyte material according to this embodiment, it is important to appropriately adjust each of the above steps. However, the method for producing a sulfide-based inorganic solid electrolyte material according to the present embodiment is not limited to the above method, and by appropriately adjusting various conditions, the sulfide-based inorganic solid electrolyte material according to the present embodiment. A solid electrolyte material can be obtained.

[Solid electrolyte]
Next, the solid electrolyte according to the present embodiment will be described. The solid electrolyte according to the present embodiment includes the sulfide-based inorganic solid electrolyte material according to the present embodiment.
And although the solid electrolyte which concerns on this embodiment is not specifically limited, For example, in this range which does not impair the objective of this invention as components other than the sulfide type inorganic solid electrolyte material which concerns on this embodiment, this embodiment mentioned above. The sulfide-based inorganic solid electrolyte material according to the present invention may include a different type of solid electrolyte material.

  The solid electrolyte according to the present embodiment may include a different type of solid electrolyte material from the sulfide-based inorganic solid electrolyte material according to the present embodiment described above. The type of solid electrolyte material different from the sulfide-based inorganic solid electrolyte material according to the present embodiment is not particularly limited as long as it has ion conductivity and insulating properties, but is generally used for lithium ion batteries. Can be used. For example, inorganic solid electrolyte materials such as sulfide-based inorganic solid electrolyte materials, oxide-based inorganic solid electrolyte materials, and other lithium-based inorganic solid electrolyte materials that are different from the sulfide-based inorganic solid electrolyte materials according to the present embodiment; Examples thereof include organic solid electrolyte materials such as polymer electrolytes.

Examples of the sulfide-based inorganic solid electrolyte material different from the sulfide-based inorganic solid electrolyte material according to the embodiment described above include, for example, Li ₂ S—P ₂ S ₅ material, Li ₂ S—SiS ₂ material, and Li ₂ S. -GeS _{2 material, Li 2 S-Al 2 S} 3 _{material, Li 2 S-SiS 2 -Li} 3 PO 4 _{material, Li 2 S-P 2 S} 5 -GeS 2 _{material, Li 2 S-Li 2 O} -P ₂ S ₅ -SiS _{2 material, Li 2 S-GeS 2 -P} 2 S 5 -SiS 2 _{material, Li 2 S-SnS 2 -P} 2 S 5 -SiS 2 _{material, Li 2 S-P 2 S} 5 -Li ₃ N _{materials, Li 2 S 2 + X -P} 4 S 3 _{material, Li 2 S-P 2 S} 5 -P 4 S 3 material, and the like. These may be used individually by 1 type and may be used in combination of 2 or more type.
Among these, Li ₂ S—P ₂ S ₅ material is preferable because it is excellent in lithium ion conductivity and has stability that does not cause decomposition in a wide voltage range. Here, for example, the Li ₂ S—P ₂ S ₅ material is an inorganic material obtained by chemically reacting an inorganic composition containing at least Li ₂ S (lithium sulfide) and P ₂ S ₅ with each other by mechanical treatment. Means material.
Here, in this embodiment, lithium polysulfide is also included in lithium sulfide.

Examples of the oxide-based inorganic solid electrolyte material include NASICON types such as LiTi ₂ (PO ₄ ) ₃ , LiZr ₂ (PO ₄ ) ₃ , LiGe ₂ (PO ₄ ) ₃ , and (La _{0.5 + x} Li _{0.5 −3x} ) TiO _{3 and} other perovskite types, Li ₂ O—P ₂ O ₅ materials, Li ₂ O—P ₂ O ₅ —Li ₃ N materials, and the like.
Examples of other lithium-based inorganic solid electrolyte materials include LiPON, LiNbO ₃ , LiTaO ₃ , Li ₃ PO ₄ , LiPO _4-x N _x (x is 0 <x ≦ 1), LiN, LiI, LISICON, and the like. It is done.
Furthermore, glass ceramics obtained by precipitating these inorganic solid electrolyte crystals can also be used as the inorganic solid electrolyte material.

As the organic solid electrolyte material, for example, a polymer electrolyte such as a dry polymer electrolyte or a gel electrolyte can be used.
As a polymer electrolyte, what is generally used for a lithium ion battery can be used.

[Solid electrolyte membrane]
Next, the solid electrolyte membrane according to the present embodiment will be described.
The solid electrolyte membrane according to the present embodiment includes a solid electrolyte containing the sulfide-based inorganic solid electrolyte material according to the present embodiment as a main component.

The solid electrolyte membrane according to the present embodiment is used for, for example, a solid electrolyte layer constituting an all solid-state lithium ion battery.
As an example of the all-solid-state lithium ion battery to which the solid electrolyte membrane according to the present embodiment is applied, a battery in which a positive electrode, a solid electrolyte layer, and a negative electrode are stacked in this order can be given. In this case, the solid electrolyte layer is constituted by a solid electrolyte membrane.

  The average thickness of the solid electrolyte membrane according to this embodiment is preferably 5 μm or more and 500 μm or less, more preferably 10 μm or more and 200 μm or less, and further preferably 20 μm or more and 100 μm or less. When the average thickness of the solid electrolyte membrane is equal to or more than the lower limit value, it is possible to further suppress the loss of the solid electrolyte and the occurrence of cracks on the surface of the solid electrolyte membrane. Moreover, the impedance of a solid electrolyte membrane can be further reduced as the average thickness of the said solid electrolyte membrane is below the said upper limit. As a result, the battery characteristics of the obtained all solid-state lithium ion battery can be further improved.

The solid electrolyte membrane according to the present embodiment is preferably a particulate solid electrolyte pressure-molded body containing the sulfide-based inorganic solid electrolyte material according to the present embodiment described above. That is, it is preferable to pressurize the particulate solid electrolyte to obtain a solid electrolyte membrane having a certain strength due to the anchor effect between the solid electrolyte materials.
By using a pressure-molded body, the solid electrolytes are bonded to each other, and the strength of the obtained solid electrolyte membrane is further increased. As a result, it is possible to further suppress the occurrence of solid electrolyte loss and cracks on the surface of the solid electrolyte membrane.

The content of the sulfide-based inorganic solid electrolyte material according to the present embodiment in the solid electrolyte membrane according to the present embodiment is preferably 50% by mass or more when the entire solid electrolyte membrane is 100% by mass. Preferably it is 60 mass% or more, More preferably, it is 70 mass% or more, More preferably, it is 80 mass% or more, Most preferably, it is 90 mass% or more. Thereby, the contact property between solid electrolytes is improved and the interfacial contact resistance of a solid electrolyte membrane can be reduced. As a result, the lithium ion conductivity of the solid electrolyte membrane can be further improved. And the battery characteristic of the all-solid-state type lithium ion battery obtained can be further improved by using such a solid electrolyte membrane excellent in lithium ion conductivity.
Although the upper limit of content of the sulfide type inorganic solid electrolyte material which concerns on this embodiment in the solid electrolyte membrane which concerns on this embodiment is not specifically limited, For example, it is 100 mass% or less.

  The planar shape of the solid electrolyte membrane is not particularly limited, and can be appropriately selected according to the shape of the electrode and the current collector. For example, the solid electrolyte membrane can be rectangular.

Further, the solid electrolyte membrane according to this embodiment may contain a binder resin, but the content of the binder resin is preferably less than 0.5% by mass when the entire solid electrolyte membrane is 100% by mass. More preferably, it is 0.1 mass% or less, More preferably, it is 0.05 mass% or less, More preferably, it is 0.01 mass% or less. Further, the solid electrolyte membrane according to this embodiment is still more preferably substantially free of binder resin, and most preferably free of binder resin.
Thereby, the contact property between solid electrolytes is improved and the interfacial contact resistance of a solid electrolyte membrane can be reduced. As a result, the lithium ion conductivity of the solid electrolyte membrane can be further improved. And the battery characteristic of the obtained all-solid-type lithium ion battery can be improved by using the solid electrolyte membrane excellent in such lithium ion conductivity.
Note that “substantially free of binder resin” means that it may be contained to the extent that the effects of the present embodiment are not impaired. Further, when an adhesive resin layer is provided between the solid electrolyte layer and the positive electrode or the negative electrode, the adhesive resin derived from the adhesive resin layer present in the vicinity of the interface between the solid electrolyte layer and the adhesive resin layer is expressed as “solid electrolyte It is removed from “binder resin in the film”.

  The binder resin refers to a binder generally used for lithium ion batteries in order to bind between inorganic solid electrolyte materials. For example, polyvinyl alcohol, polyacrylic acid, carboxymethyl cellulose, polytetrafluoro Examples include ethylene, polyvinylidene fluoride, styrene / butadiene rubber, and polyimide.

The solid electrolyte membrane according to the present embodiment is obtained by, for example, depositing a particulate solid electrolyte in a film shape on the cavity surface of a mold or on a substrate surface, and then pressurizing the solid electrolyte deposited in the film shape. Obtainable.
The method of pressurizing the solid electrolyte is not particularly limited. For example, when a particulate solid electrolyte is deposited on the cavity surface of the mold, pressing with a mold and a pressing mold, the particulate solid electrolyte is applied to the substrate surface. In the case of depositing on the top, a press using a die and a pressing die, a roll press, a flat plate press or the like can be used.
The pressure for pressurizing the solid electrolyte is, for example, 10 MPa or more and 500 MPa or less.

If necessary, the inorganic solid electrolyte deposited in a film shape may be pressurized and heated. If heating and pressurization are performed, the solid electrolytes are fused and bonded, and the strength of the obtained solid electrolyte membrane is further increased. As a result, it is possible to further suppress the occurrence of solid electrolyte loss and cracks on the surface of the solid electrolyte membrane.
The temperature which heats a solid electrolyte is 40 degreeC or more and 500 degrees C or less, for example.

[Lithium ion battery]
FIG. 1 is a cross-sectional view showing an example of the structure of a lithium ion battery 100 according to an embodiment of the present invention.
The lithium ion battery 100 according to the present embodiment includes, for example, a positive electrode 110 including a positive electrode active material layer 101, an electrolyte layer 120, and a negative electrode 130 including a negative electrode active material layer 103. At least one of the positive electrode active material layer 101, the negative electrode active material layer 103, and the electrolyte layer 120 contains the sulfide-based inorganic solid electrolyte material according to this embodiment. Moreover, it is preferable that all of the positive electrode active material layer 101, the negative electrode active material layer 103, and the electrolyte layer 120 contain the sulfide-based inorganic solid electrolyte material according to the present embodiment. Note that in this embodiment, a layer containing a positive electrode active material is referred to as a positive electrode active material layer 101 unless otherwise specified. The positive electrode 110 may further include a current collector 105 in addition to the positive electrode active material layer 101 as necessary, or may not include the current collector 105. In this embodiment, a layer containing a negative electrode active material is referred to as a negative electrode active material layer 103 unless otherwise specified. The negative electrode 130 may further include a current collector 105 in addition to the negative electrode active material layer 103 or may not include the current collector 105 as necessary.
The shape of the lithium ion battery 100 according to the present embodiment is not particularly limited, and examples thereof include a cylindrical shape, a coin shape, a square shape, a film shape, and other arbitrary shapes.

  The lithium ion battery 100 according to the present embodiment is generally manufactured according to a known method. For example, by stacking the positive electrode 110, the electrolyte layer 120, and the negative electrode 130 into a cylindrical shape, a coin shape, a square shape, a film shape, or any other shape, and encapsulating a non-aqueous electrolyte as necessary Produced.

(Positive electrode)
The positive electrode 110 is not particularly limited, and those commonly used for lithium ion batteries can be used. The positive electrode 110 is not particularly limited, but can be generally manufactured according to a known method. For example, it can be obtained by forming a positive electrode active material layer 101 containing a positive electrode active material on the surface of a current collector 105 such as an aluminum foil.
The thickness and density of the positive electrode active material layer 101 are not particularly limited because they are appropriately determined according to the intended use of the battery, and can be generally set according to known information.

The positive electrode active material layer 101 includes a positive electrode active material.
The positive electrode active material is not particularly limited, and generally known materials can be used. For example, lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium manganese oxide (LiMn ₂ O ₄ ), solid solution oxide (Li ₂ MnO ₃ —LiMO ₂ (M = Co, Ni, etc.)) ), Lithium-manganese-nickel oxide (LiNi _1/3 Mn _1/3 Co _1/3 O ₂ ), olivine-type lithium phosphorus oxide (LiFePO ₄ ) and other complex oxides; polyaniline, polypyrrole and other highly conductive materials _{molecule; Li 2 S, CuS, Li} -CuS _{compounds, TiS 2, FeS, MoS 2} , Li-MoS compounds, Li-TiS compounds, Li-V-S compounds, Li-FeS compound Sulfide-based positive electrode active materials such as acetylene black impregnated with sulfur, porous carbon impregnated with sulfur, sulfur and carbon mixed powder, etc. And materials; and the like can be used. These positive electrode active materials may be used individually by 1 type, and may be used in combination of 2 or more type.
Among these, from the viewpoint of having a higher discharge capacity density and more excellent cycle characteristics, a sulfide-based positive electrode active material is preferable, and a Li—Mo—S compound, a Li—Ti—S compound, a Li—V—S is preferable. One or more selected from compounds are more preferred.

Here, the Li—Mo—S compound contains Li, Mo, and S as constituent elements, and an inorganic composition containing molybdenum sulfide and lithium sulfide, which are usually raw materials, is chemically treated by mechanical treatment. It can be obtained by reacting.
Further, the Li—Ti—S compound contains Li, Ti, and S as constituent elements, and an inorganic composition containing titanium sulfide and lithium sulfide, which are usually raw materials, is chemically reacted with each other by mechanical treatment. Can be obtained.
The Li-VS compound contains Li, V, and S as constituent elements, and an inorganic composition containing vanadium sulfide and lithium sulfide, which are usually raw materials, is chemically reacted with each other by mechanical treatment. Can be obtained.

  Although the positive electrode active material layer 101 is not particularly limited, the component other than the positive electrode active material may include, for example, one or more materials selected from a binder resin, a thickener, a conductive additive, a solid electrolyte material, and the like. . Hereinafter, each material will be described.

The positive electrode active material layer 101 may include a binder resin having a role of binding the positive electrode active materials to each other and the positive electrode active material and the current collector 105.
The binder resin according to the present embodiment is not particularly limited as long as it is a normal binder resin that can be used for a lithium ion battery. For example, polyvinyl alcohol, polyacrylic acid, carboxymethyl cellulose, polytetrafluoroethylene, polyvinylidene fluoride, styrene Examples thereof include butadiene rubber and polyimide. These binders may be used alone or in combination of two or more.

  The positive electrode active material layer 101 may contain a thickener from the viewpoint of ensuring the fluidity of the slurry suitable for application. The thickener is not particularly limited as long as it is a normal thickener usable for lithium ion batteries. For example, cellulose polymers such as carboxymethylcellulose, methylcellulose, hydroxypropylcellulose, and ammonium salts and alkali metal salts thereof. Examples thereof include water-soluble polymers such as polycarboxylic acid, polyethylene oxide, polyvinyl pyrrolidone, polyacrylate, and polyvinyl alcohol. These thickeners may be used individually by 1 type, and may be used in combination of 2 or more types.

  From the viewpoint of improving the conductivity of the positive electrode 110, the positive electrode active material layer 101 may include a conductive additive. The conductive auxiliary agent is not particularly limited as long as it is a normal conductive auxiliary agent that can be used for a lithium ion battery, and examples thereof include carbon blacks such as acetylene black and ketjen black, and carbon materials such as vapor grown carbon fibers. .

  The positive electrode according to the present embodiment may include a solid electrolyte including the sulfide-based inorganic solid electrolyte material according to the present embodiment described above, or a type different from the sulfide-based inorganic solid electrolyte material according to the present embodiment. A solid electrolyte containing a solid electrolyte material may be included. The type of solid electrolyte material different from the sulfide-based inorganic solid electrolyte material according to the present embodiment is not particularly limited as long as it has ion conductivity and insulating properties, but is generally used for lithium ion batteries. Can be used. Examples thereof include inorganic solid electrolyte materials such as sulfide-based inorganic solid electrolyte materials, oxide-based inorganic solid electrolyte materials, and other lithium-based inorganic solid electrolyte materials; organic solid electrolyte materials such as polymer electrolytes. More specifically, the inorganic solid electrolyte materials mentioned in the description of the solid electrolyte according to this embodiment can be used.

  The mixing ratio of various materials in the positive electrode active material layer 101 is not particularly limited because it is appropriately determined according to the intended use of the battery and the like, and can be generally set according to known information.

(Negative electrode)
The negative electrode 130 is not specifically limited, What is generally used for the lithium ion battery can be used. The negative electrode 130 is not particularly limited, but can be generally manufactured according to a known method. For example, it can be obtained by forming a negative electrode active material layer 103 containing a negative electrode active material on the surface of a current collector 105 such as copper.
The thickness and density of the negative electrode active material layer 103 are not particularly limited because they are appropriately determined according to the intended use of the battery and the like, and can generally be set according to known information.

The negative electrode active material layer 103 includes a negative electrode active material.
The negative electrode active material is not particularly limited as long as it is a normal negative electrode active material that can be used for a negative electrode of a lithium ion battery. For example, natural graphite, artificial graphite, resin charcoal, carbon fiber, activated carbon, hard carbon, soft carbon Carbonaceous materials such as lithium, lithium alloys, tin, tin alloys, silicon, silicon alloys, gallium, gallium alloys, indium, indium alloys, aluminum, aluminum alloys, etc .; polyacene, polyacetylene, polypyrrole, etc. A conductive polymer of lithium titanium composite oxide (for example, Li ₄ Ti ₅ O ₁₂ ) and the like. These negative electrode active materials may be used individually by 1 type, and may be used in combination of 2 or more type.

Although the negative electrode active material layer 103 is not particularly limited, the component other than the negative electrode active material may include, for example, one or more materials selected from a binder resin, a thickener, a conductive additive, a solid electrolyte material, and the like. . These materials are not particularly limited, and examples thereof include the same materials as those used for the positive electrode 110 described above.
The mixing ratio of various materials in the negative electrode active material layer 103 is not particularly limited because it is appropriately determined according to the intended use of the battery and the like, and can generally be set according to known information.

(Electrolyte layer)
Next, the electrolyte layer 120 will be described. The electrolyte layer 120 is a layer formed between the positive electrode active material layer 101 and the negative electrode active material layer 103.
Examples of the electrolyte layer 120 include those in which a separator is impregnated with a nonaqueous electrolytic solution, and solid electrolyte layers containing a solid electrolyte.

  The separator according to the present embodiment is not particularly limited as long as it has a function of electrically insulating the positive electrode 110 and the negative electrode 130 and transmitting lithium ions. For example, a porous film can be used.

  A microporous polymer film is preferably used as the porous film, and examples of the material include polyolefin, polyimide, polyvinylidene fluoride, and polyester. In particular, a porous polyolefin film is preferable, and specific examples include a porous polyethylene film and a porous polypropylene film.

The non-aqueous electrolyte is obtained by dissolving an electrolyte in a solvent.
As the electrolyte, any known lithium salt can be used, and may be selected according to the type of active material. For _{example, LiClO 4, LiBF 6, LiPF} 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, LiAlCl 4, LiCl, LiBr, LiB (C 2 H 5) 4, CF 3 Examples include SO ₃ Li, CH ₃ SO ₃ Li, LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, and lower fatty acid carboxylate lithium.

  The solvent for dissolving the electrolyte is not particularly limited as long as it is usually used as a liquid for dissolving the electrolyte. Ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC) Carbonates such as diethyl carbonate (DEC), methyl ethyl carbonate (MEC), vinylene carbonate (VC); lactones such as γ-butyrolactone and γ-valerolactone; trimethoxymethane, 1,2-dimethoxyethane, diethyl ether Ethers such as 2-ethoxyethane, tetrahydrofuran and 2-methyltetrahydrofuran; sulfoxides such as dimethyl sulfoxide; oxolanes such as 1,3-dioxolane and 4-methyl-1,3-dioxolane; Nitrogens such as ril, nitromethane, formamide, dimethylformamide; organic acid esters such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate; phosphate triesters and diglymes; Sulfolanes such as sulfolane and methylsulfolane; oxazolidinones such as 3-methyl-2-oxazolidinone; sultones such as 1,3-propane sultone, 1,4-butane sultone and naphtha sultone; These may be used individually by 1 type and may be used in combination of 2 or more type.

The solid electrolyte layer according to the present embodiment is a layer formed between the positive electrode active material layer 101 and the negative electrode active material layer 103, and is a layer formed of a solid electrolyte containing a solid electrolyte material. The solid electrolyte contained in the solid electrolyte layer is not particularly limited as long as it has lithium ion conductivity. In the present embodiment, the solid electrolyte includes a sulfide-based inorganic solid electrolyte material according to the present embodiment. An electrolyte is preferred.
The content of the solid electrolyte in the solid electrolyte layer according to the present embodiment is not particularly limited as long as a desired insulating property is obtained, but for example, within a range of 10% by volume to 100% by volume, Especially, it is preferable that it exists in the range of 50 volume% or more and 100 volume% or less. In particular, in the present embodiment, it is preferable that the solid electrolyte layer is composed only of a solid electrolyte including the sulfide-based inorganic solid electrolyte material according to the present embodiment.

  Moreover, the solid electrolyte layer according to the present embodiment may contain a binder resin. By containing the binder resin, a flexible solid electrolyte layer can be obtained. Examples of the binder resin include fluorine-containing binders such as polytetrafluoroethylene and polyvinylidene fluoride. The thickness of the solid electrolyte layer is, for example, preferably in the range of 0.1 μm to 1000 μm, and more preferably in the range of 0.1 μm to 300 μm.

As mentioned above, although embodiment of this invention was described, these are illustrations of this invention and various structures other than the above are also employable.
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

  Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited to these.

[1] Measuring Method First, measuring methods in the following examples and comparative examples will be described.

(1) Particle size distribution Particle size distribution of sulfide-based inorganic solid electrolyte materials obtained in Examples and Comparative Examples by a laser diffraction method using a laser diffraction / scattering particle size distribution measuring device (manufactured by Malvern, Mastersizer 3000). Was measured. From the measurement results, the particle size (D ₅₀ , average particle size) at 50% accumulation in the weight-based cumulative distribution was determined for the sulfide-based inorganic solid electrolyte material.

(2) Measurement of composition ratio Sulfide-based inorganic solid electrolytes obtained in Examples and Comparative Examples were measured by ICP emission spectroscopic analysis using an ICP emission spectroscopic analyzer (manufactured by Seiko Instruments Inc., SPS3000). The mass percentages of Li, P and S in the material were determined, and the molar ratio of each element was calculated based on the mass%.

(3) X-ray diffraction analysis Using an X-ray diffractometer (RINT2000, RINT2000), the diffraction spectra of the sulfide-based inorganic solid electrolyte materials obtained in the examples and comparative examples were obtained by X-ray diffraction analysis, respectively. Asked. Note that CuKα rays were used as the radiation source. Here, the maximum diffraction intensity at the position of the diffraction angle 2θ = 35.0 ± 0.1 ° is defined as the background intensity I _0, and the maximum of the diffraction peaks existing at the position of the diffraction angle 2θ = 17.2 ± 0.5 °. the diffraction intensity and _{I a,} the maximum diffraction intensity of a diffraction peak at the position of the diffraction angle 2θ = 29.2 ± 0.8 ° and _{I B,} the position of the diffraction angle 2θ = 25.6 ± 0.5 ° the maximum diffraction intensity of the diffraction peak present was I _{C. Further,} I determined _{I A / I 0, I B} / I 0 and _I A / _{I B,} respectively.

(4) Measurement of lithium ion conductivity Lithium ion conductivity was measured by the alternating current impedance method for the sulfide-based inorganic solid electrolyte materials obtained in Examples and Comparative Examples, and evaluated according to the following criteria.
A: 1.3 × 10 ⁻³ S · cm ⁻¹ or more ○: 1.1 × 10 ⁻³ S · cm ⁻¹ or more and less than 1.3 × 10 ⁻³ S · cm ⁻¹ ×: 0.80 × 10 ^-3 S · cm ⁻¹ or more and 1.1 × 10 ⁻³ S · cm ^{−1 or} less XX: 0.60 × 10 ⁻³ S · cm ⁻¹ or more and less than 0.80 × 10 ⁻³ S · cm ⁻¹ XXX: Less than 0.60 × 10 ⁻³ S · cm ⁻¹ Lithium ion conductivity was measured using a potentiostat / galvanostat SP-300 manufactured by Biologic. The size of the sample is 9.5 mm in diameter, 1.2 to 2.0 mm in thickness, the measurement conditions are applied voltage 10 mV, measurement temperature 27.0 ° C., measurement frequency range 0.1 Hz to 7 MHz, and the electrode is Li foil. .
Here, a sample for measuring lithium ion conductivity is obtained by pressing 150 mg of powdered sulfide-based inorganic solid electrolyte material obtained in Examples and Comparative Examples at 270 MPa for 10 minutes using a pressing device. A plate-shaped sulfide-based inorganic solid electrolyte material having a diameter of 9.5 mm and a thickness of 1.2 to 2.0 mm was used.

(5) Measurement of maximum value of oxidative decomposition current Using a pressing device, 120 to 150 mg of powdered sulfide-based inorganic solid electrolyte material obtained in Examples and Comparative Examples was pressed at 270 MPa for 10 minutes and a diameter of 9. A plate-like sulfide-based inorganic solid electrolyte material (pellet) having a thickness of 5 mm and a thickness of 1.3 mm was obtained. Subsequently, Li foil as a reference electrode / counter electrode was press-pressed under a condition of 18 MPa for 10 minutes on one surface of the obtained pellet, and SUS314 foil was adhered as a working electrode to the other surface.
Subsequently, using a potentiostat / galvanostat SP-300 manufactured by Biologic, Inc., oxidative decomposition of the sulfide-based inorganic solid electrolyte material under the conditions of a temperature of 25 ° C., a sweep voltage range of 0 to 5 V, and a voltage sweep rate of 5 mV / sec. The maximum value of current was obtained and evaluated according to the following criteria.
A: 0.03 μA or less O: 0.03 μA exceeded 0.50 μA or less X: 0.50 μA exceeded

[2] Production of solid electrolyte material <Example 1>
A sulfide-based inorganic solid electrolyte material was prepared by the following procedure.
Li ₂ S (Furukawa Machine Metal Co., Ltd., purity 99.9%), P ₂ S ₅ (Kanto Chemical Co., Inc.) and Li ₃ N (Furukawa Machine Metal Co., Ltd.) were used as raw materials.
First, a rotary blade type pulverizer and an alumina pot (with an internal volume of 400 mL) are placed in the glove box, and then high purity dry argon gas (H Injection of ₂ O <1 ppm, O ₂ <1 ppm) and vacuum deaeration were performed three times.
Next, in the glove box, using a rotary blade type pulverizer (rotation speed 18000 rpm), Li ₂ S powder, P ₂ S ₅ powder and Li ₃ N powder (Li ₂ S: P ₂ S ₅ : Li ₃ N) = 71.1: 23.7: 5.3 (mol%)) 5 g in total (mixing 10 seconds and standing 10 seconds 10 times (total mixing time: 100 seconds)) A raw material inorganic composition was prepared.
Here, the charging of the Li ₂ S powder, the P ₂ S ₅ powder and the Li ₃ N powder into the rotary blade crusher in the glove box was performed according to the following procedure. First, Li ₂ S powder, P ₂ S ₅ powder and Li ₃ N powder were placed in the side box of the glove box with the door inside the main body of the glove box closed. Next, injection of high-purity dry argon gas guided from the inside of the glove box and vacuum deaeration were performed three times in the side box. Next, the door inside the main body of the glove box was opened, Li ₂ S powder, P ₂ S ₅ powder and Li ₃ N powder were put in a rotary blade type pulverizer inside the main body of the glove box, and the pulverizer was sealed.

Subsequently, the raw material inorganic composition and 500 g of ZrO ₂ balls having a diameter of 10 mm were put into an alumina pot (internal volume 400 mL) in the glove box, and the pot was sealed. Here, an O-ring (standard P-75) was used as the packing in the lid portion of the pot made of alumina. Further, dry argon gas was circulated in the glove box, and the water concentration was adjusted to 0.5 ppm and the oxygen concentration was adjusted to 0.6 ppm.
Next, the alumina pot is taken out from the glove box, and the alumina pot is attached to a ball mill installed in a dry air atmosphere introduced through a membrane air dryer, and mixed at 120 rpm for 500 hours, and the raw material inorganic composition The material was vitrified. At this time, the moisture concentration of the dry air obtained through the membrane air dryer was 600 ppm. Every 48 hours of mixing, the powder on the inner wall of the pot was scraped off in the glove box, and after sealing, milling was continued in a dry atmosphere.
Next, an alumina pot was placed in the glove box, and the obtained powder was transferred from the alumina pot to a carbon crucible, and subjected to heat treatment at 270 ° C. for 2 hours in a heating furnace installed in the glove box.
Each evaluation was performed about the obtained sulfide type inorganic solid electrolyte material. The obtained results are shown in Table 1.

<Example 2>
The mixing ratio of Li ₂ S powder, P ₂ S ₅ powder and Li ₃ N powder was changed to Li ₂ S: P ₂ S ₅ : Li ₃ N = 73.8: 24.6: 1.6 (mol%). Except for the above, a sulfide-based inorganic solid electrolyte material was prepared in the same manner as in Example 1, and each evaluation was performed. The obtained results are shown in Table 1, respectively.

<Example 3>
Implemented except that the mixing ratio of Li ₂ S powder and P ₂ S ₅ powder was changed to Li ₂ S: P ₂ S ₅ = 75.0: 25.0 (mol%) without using Li ₃ N powder. A sulfide-based inorganic solid electrolyte material was produced in the same manner as in Example 1, and each evaluation was performed. The obtained results are shown in Table 1, respectively.

<Comparative Example 1>
A sulfide-based inorganic solid electrolyte material was prepared and evaluated in the same manner as in Example 1 except that the moisture concentration of dry argon in the glove box was changed to 10.7 ppm and the oxygen concentration was changed to 1.0 ppm. The obtained results are shown in Table 1, respectively.

<Comparative example 2>
A sulfide-based inorganic solid electrolyte material was prepared and evaluated in the same manner as in Example 2 except that the moisture concentration of dry argon in the glove box was changed to 10.7 ppm and the oxygen concentration was changed to 1.0 ppm. The obtained results are shown in Table 1, respectively.

<Comparative Example 3>
A sulfide-based inorganic solid electrolyte material was prepared and evaluated in the same manner as in Example 3 except that the moisture concentration of dry argon in the glove box was changed to 10.7 ppm and the oxygen concentration was changed to 1.0 ppm. The obtained results are shown in Table 1, respectively.

The sulfide-based inorganic solid electrolyte materials of Examples 1 to 3 were excellent in lithium ion conductivity and electrochemical stability. In contrast, the sulfide-based inorganic solid electrolyte materials of Comparative Examples 1 to 3 were inferior in lithium ion conductivity.
Here, X-ray diffraction spectra of the sulfide-based inorganic solid electrolyte materials obtained in Example 1 and Comparative Example 1 are shown in FIG. Further, X-ray diffraction spectra of the sulfide-based inorganic solid electrolyte materials obtained in Example 2 and Comparative Example 2 are shown in FIG. In addition, X-ray diffraction spectra of the sulfide-based inorganic solid electrolyte materials obtained in Example 3 and Comparative Example 3 are shown in FIG.

DESCRIPTION OF SYMBOLS 100 Lithium ion battery 101 Positive electrode active material layer 103 Negative electrode active material layer 105 Current collector 110 Positive electrode 120 Electrolyte layer 130 Negative electrode

Claims (18)

A sulfide-based inorganic solid electrolyte material having lithium ion conductivity,
In the spectrum obtained by X-ray diffraction using CuKα ray as the radiation source, there are peaks at the diffraction angle 2θ = 17.2 ± 0.5 ° and the diffraction angle 2θ = 29.2 ± 0.8 °, respectively. And
Maximum diffraction of the diffraction peak maximum diffraction intensity of a diffraction peak at the position of the diffraction angle 2θ = 17.2 ± 0.5 ° and _{I A,} at the position of the diffraction angle 2θ = 29.2 ± 0.8 ° when the strength was _{I B,
A} sulfide-based inorganic solid electrolyte material having a value of I _A / I _B of 0.92 or more. The sulfide-based inorganic solid electrolyte material according to claim 1,
In the spectrum obtained by X-ray diffraction using CuKα ray as the radiation source, when the maximum diffraction intensity at the diffraction angle 2θ = 35.0 ± 0.1 ° is the background intensity I ₀ , I _A / I ₀ A sulfide-based inorganic solid electrolyte material having a value of 8.0 or more. The sulfide-based inorganic solid electrolyte material according to claim 1 or 2,
In the spectrum obtained by X-ray diffraction using CuKα ray as the radiation source, when the maximum diffraction intensity at the diffraction angle 2θ = 35.0 ± 0.1 ° is the background intensity I ₀ , I _B / I ₀ A sulfide-based inorganic solid electrolyte material having a value of 5.0 or more. In the sulfide system inorganic solid electrolyte material according to any one of claims 1 to 3,
A sulfide-based inorganic solid electrolyte material further having a diffraction peak at a diffraction angle 2θ = 25.6 ± 0.5 ° in a spectrum obtained by X-ray diffraction using CuKα rays as a radiation source. A sulfide-based inorganic solid electrolyte material having lithium ion conductivity,
After heat treatment at 270 ° C. for 2 hours, in a spectrum obtained by X-ray diffraction using CuKα rays as a radiation source, a diffraction angle 2θ = 17.2 ± 0.5 ° and a diffraction angle 2θ = 29.2 ± 0. Each has a peak at 8 °,
Maximum diffraction of the diffraction peak maximum diffraction intensity of a diffraction peak at the position of the diffraction angle 2θ = 17.2 ± 0.5 ° and _{I A,} at the position of the diffraction angle 2θ = 29.2 ± 0.8 ° when the strength was _{I B,
A} sulfide-based inorganic solid electrolyte material having a value of I _A / I _B of 0.92 or more. The sulfide-based inorganic solid electrolyte material according to claim 5,
After heat treatment at 270 ° C. for 2 hours, the maximum diffraction intensity at the position of diffraction angle 2θ = 35.0 ± 0.1 ° in the spectrum obtained by X-ray diffraction using CuKα ray as the radiation source is the background intensity I _0. , _A sulfide-based inorganic solid electrolyte material having a value of I _A / I ₀ of 8.0 or more. The sulfide-based inorganic solid electrolyte material according to claim 5 or 6,
After heat treatment at 270 ° C. for 2 hours, the maximum diffraction intensity at the position of diffraction angle 2θ = 35.0 ± 0.1 ° in the spectrum obtained by X-ray diffraction using CuKα ray as the radiation source is the background intensity I _0. , A sulfide-based inorganic solid electrolyte material having a value of I _B / I ₀ of 5.0 or more. The sulfide-based inorganic solid electrolyte material according to any one of claims 5 to 7,
A sulfide-based inorganic material further having a diffraction peak at a diffraction angle 2θ = 25.6 ± 0.5 ° in a spectrum obtained by X-ray diffraction using CuKα ray as a radiation source after heat treatment at 270 ° C. for 2 hours. Solid electrolyte material. The sulfide based inorganic solid electrolyte material according to any one of claims 1 to 8,
A sulfide-based inorganic solid electrolyte material containing Li, P and S as constituent elements. The sulfide-based inorganic solid electrolyte material according to claim 9,
The molar ratio Li / P of the content of Li to the content of P in the sulfide-based inorganic solid electrolyte material is 1.0 or more and 5.0 or less, and the content of S relative to the content of P A sulfide-based inorganic solid electrolyte material having a molar ratio S / P of 2.0 or more and 6.0 or less. In the sulfide system inorganic solid electrolyte material according to any one of claims 1 to 10,
The shape of the sulfide-based inorganic solid electrolyte material is particulate,
In weight particle size distribution by a laser diffraction scattering particle size distribution measuring method, particulate serial sulfide-based inorganic solid electrolyte average particle size d ₅₀ of material is 1μm or more 100μm or less sulfide-based inorganic solid electrolyte material. The sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 11,
A sulfide-based inorganic solid electrolyte material used in lithium ion batteries.   The solid electrolyte containing the sulfide type inorganic solid electrolyte material as described in any one of Claims 1 thru | or 12.   A solid electrolyte membrane comprising the solid electrolyte according to claim 13 as a main component. The solid electrolyte membrane according to claim 14,
A solid electrolyte membrane which is a pressure-formed body of the particulate solid electrolyte. The solid electrolyte membrane according to claim 14 or 15,
A solid electrolyte membrane in which the content of the binder resin in the solid electrolyte membrane is less than 0.5 mass% when the entire solid electrolyte membrane is 100 mass%. The solid electrolyte membrane according to any one of claims 14 to 16,
A solid electrolyte membrane in which the content of the sulfide-based inorganic solid electrolyte material in the solid electrolyte membrane is 50% by mass or more when the entire solid electrolyte membrane is 100% by mass. A lithium ion battery comprising a positive electrode including a positive electrode active material layer, an electrolyte layer, and a negative electrode including a negative electrode active material layer,
The lithium ion battery in which at least one of the positive electrode active material layer, the electrolyte layer, and the negative electrode active material layer includes the sulfide-based inorganic solid electrolyte material according to any one of claims 1 to 12.

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